The main objectives in our proposed hemoglobin research are: (1) to understand the molecular mechanism for the cooperative oxygenation of human adult hemoglobin and (2) to correlate the structure-function relationships in human abnormal hemoglobins found in hemoglobinopathies. Our basic experimental approach is to apply physical-chemical techniques, in particular, nuclear magnetic resonance (NMR) spectroscopy, to pinpoint spectral differences among hemoglobins. By choosing appropriate human mutant hemoglobins and by making use of Perutz's atomic models of hemoglobin, we have found that NMR spectroscopy can provide detailed and in some cases unique information about the heme environment, functional properties of the heme groups, and the nature of subunit interactions during the oxygenation process. We would like to continue and to expand our NMR studies of hemoglobins.